US Pharm. 2018;43(2):2.
As if there isn’t enough to worry about during this intense influenza season, patients can add myocardial infarction to the list of possible comorbidities. Late last month, a study published in the New England Journal of Medicine showed that the flu may also heighten the risk of a myocardial infarction.
In fact, the study, authored by Canadian scientists, demonstrated a substantial increase in heart attacks shortly following a flu diagnosis. Dr. Jeff Kwong, lead study author, Institute for Clinical Evaluative Sciences and Public Health Ontario, put it bluntly. “We found that your risk of a heart attack is six times higher in the first week after the diagnosis of influenza,” he said, “which is a significant increase for that short period of time.”
Employing various high-specificity laboratory methods, the scientists looked at the association between laboratory-confirmed flu cases and hospitalization for acute myocardial infarction. They identified 364 hospitalizations for acute myocardial infarction that occurred between 1 year before and 1 year after a positive influenza test. Of these, 20 admissions per week happened during the risk interval and 3.3 admissions per week occurred during the control interval. (“Risk interval” was the first 7 days after respiratory specimen collection, and the “control interval” was 1 year before and 1 year after the risk interval.)
The resulting incidence ratio of an admission for acute myocardial infarction during the risk interval compared with the control interval was a surprising 6.05 (95% CI, 3.86-9.50), and the scientists saw no increased incidence after Day 7.
The researchers found “a significant association between respiratory infections, especially influenza, and acute myocardial infarction.” The study did not offer reasons for why influenza might trigger heart attacks. Nevertheless, researchers are gaining a greater understanding of the links between infections, inflammation, and coronary artery disease.
This news is certainly timely. The United States is in the grip of a severe flu epidemic that, at least in some regions, was still building strength in early February. Pharmacists are clearly in the forefront of preventing influenza spread and, it appears, heart attacks. According to a study in Clinical Therapeutics, pharmacist-delivered influenza vaccines resulted in 5.1 million more vaccinations between 2003 and 2013 and a growth in vaccination rates from 32.2% to 40.3%. Even more impressive, pharmacist-delivered doses grew from 3.2 million to 20.9 million over the same period.
Clearly, many people who have thus far avoided coming down with this year’s particularly virulent strain have a pharmacist to thank. The startling link between flu and heart attacks, moreover, renders the importance of flu vaccinations even greater, including those convenient doses delivered in pharmacies.
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